[TYPO3-english] to add a simple join table do i need to add a domain?

[Calgacus map Brude]

Hi,
I am building a coupon management extension and want to associate each coupon with each person (in the fe_users table) who uses it.  I want to do this by creating a third table which contains the uid of the user and the uid of the coupon.  a simple two field table.   how do i do this in typo3 v4.5.3 with extbase.  I want the third table to be part of my extension, do I need to create a new model and TCA entries?  would like to learn to do all this without extension builder just so i get my hands on all the details.

Thanks